Field of the Invention
Cots and aprons (including roll covers) are textile fiber-working units, used in the textile industry for working fibers into yarn. In the textile drafting process, these elements provide a surface for guiding and controlling the fiber as it is converted into yarns.
Certain properties of the cot and apron are important because of the effect on the quality of the yarn which is made with it. Simultaneously, it is also important to have a fiber-working element which has a practical working life. Cots and aprons do have a limited life time. As they wear out during the drafting process, they are replaced with new units. Thus, there is a continuing need for new cots and aprons. Ideally, cots and aprons should have good fiber-working characteristics and also a long life time.
Presently, cots and aprons are made with elastomeric compositions. The elastomers were developed and utilized in preference to leather, since better wear properties and more lap resistance were obtained. Elastomeric compositions based on acrylonitrilebutadiene rubber are taught in U.S. Pat. Nos. 2,450,410; 2,450,409; 2,636,878; 2,811,752; and 2,858,283. Animal glue, surfactants, and polyelectrolytes are used to obtain desired fiber-working properties. The animal glue, in particular, is widely utilized in combination with elastomers for the fiber-working surfaces of cots and aprons. Even with these elastomer compositions, however, lapping continues to be a problem for cots and sometimes aprons. Furthermore, synthetic fibers have a greater lapping problem due to the higher attraction of the fiber for the working element's surface.
In addition to this, the use of animal glue or protein requires digestion in water before combining it with the elastomer in the composition. This is a cumbersome and disadvantageous preparation procedure. This preparation procedure, moreover, calls for the introduction of water which must be completely removed in order to obtain a good fiber-working unit.
Polymer compositions which are reported to be suitable for textile cots are shown in U.S. Pat. No. 4,508,867. This reference, however, requires the presence of halide additives. These are additives which are both hydroscopic and otherwise also detrimental to properties needed in the yarn working surface. The presence of these additives has been noted to cause the fiber-working surface to collect moisture. When such additives are present, smoothness is also a problem, the additive tending to cause surface blemishes. Compositions containing these additives have poor yarn-working characteristics.
If good properties are not maintained in a fiber-working unit, a poor yarn product is the result. The invention described herein provides fiber-working elements having good to excellent fiber-handling characteristics and good wear properties. Compositions are also described which form the fiber-working unit. These compositions, furthermore, are much more easily made into cots and aprons than the compositions which contain halide additives or rely on animal glue for lap resistance and other needed fiber-working properties.